Manufacture of molded articles from latex



Patented July 5, 1927.

umren STATES PATENT-OFFICE.

cnauncnx c. Loomis, or YONKERS, ANDHORACE E. srumr, or nnooxrxu, NEW roan, ASSIGNORS, BY MESNE ASSIGNMENTS, TO THE nnvm CORPORATION, A

CDRPORA'IION OF NEW YORK.

MANUFACTURE OF MOLDED ARTICLES FROM LATEX.

. No Drawing.

This invention relates to the molding of articles, and more particularly to the molding of articles containing a percentage, preferably low, of rubber.

6 A principal object of the invention is the provision of a process for molding articles rom a low rubber content material at camparatively low cost.

Another important object of the invention 10 is the provision of a process for employing latex efficiently and economically in the production of tough, firm molded materials of low rubber content.

Uther objects and advantages of the invention Will be apparent as it is better understood from the following description of the process selected as a preferred embodiment of the invention to or on the material thereby produced.

In practicing our invention we contemplate the dry molding of a suitable mixture of latex with fillers through the coagulation of the mass in the presence of large volumes of Water, permitting the resultant rubber or partially coagulated latex to attach itself to the particles of filler rather than separating out in lump condition. Preferably a mixture of wood flour, zinc oxide or other, rubber filler together with the sulphur necessary forthe vulcanization of the rubber is suspended in Water. Along with the fillers we prefer to add a catalyst as thiocarbonalide if a hot molding is to be accomplished, this catalyst being omitted if the molded article 336 is to be cold cured. Sutlicient water is added to insure the mass being in suspension in wa ter and to this a quantity of latex is introduced. The resultant mixture is constantly agitated While a suitable coa' lant is added 40 in amount to partially coagulate or agglomerate the colloidal particles. The amount of the coagulation is suflicient, and preferably only suflicientto break the suspension and cause the filler and the coagulated material as to precipitate or settle out. If the proportions of the various in redient's have been properly chosen the'sett ing out orprecipitating of the material will not produce or form the solid mass characteristic of wage Cat) lated rubber but will produce a granulated or flaky condition. drained ofi and the material dried at a low temperature. Thereafter it may be hot mold- The water is then Application filed August 22, 1923. Serial No. 658,883.

ed by putting it in a mold and pressing and heating the same to compress the articles into a firm mass and vulcanize the rubber.

An example of a mixture is as follows: Wood flour, 15 gms.; zinc oxide orclay, 15 gms; rubber latex, 36% rubber, 10 c. c.; sulphur, 5% of rubber used; catalyst (mild and incapable of so-called cold cure) water 700 c. c. This mixture gives about a 10% rubber content in the material and it has been discovered that with such a low ercentage of rubber firm, tough materials wi 1 be molded. Manifestly the proportions may be va ried and more rubber used in some instances as desired.

Cold molding ma be accomplished by omitting the catalyst rom the above formula and molstening the proper material with a small amount of organic solvent containing a catalyst in solution. For cold curing a condensation product of carbon bisulphide, slich as tetra methyl, thiuram disulphide, etc., may be employed and the cold curing proceeded with in the ordinary manner. The material in either event, after being dried, has the form of a dry, flaky powder readily handled and easily molded.

We claim:

l. The process of molding articles, comprising, forming a suspension of a filler, adding latex, partially coagulating the latex, removing the liquid content, drying and pressing.

2. The process of molding articles, comprising, forming a suspension of a filling material and sulphur for vulcanization, adding latex, partially coagulating the latex, removing the liquid, pressing, and vulcanizing.

3. The process jh fimolding articles, comprising, forming afsuspension of a filling material and sulphun'for vulcanization, addmg latex, partia'll., coagulatingsthe latex,

removing the liqui' and vulcanizing.

4. The process of molding articles, comprising, forming a suspension of a filling material and providing suflicientwater. to hold the mass, in suspension, adding latex, partially coagulating the latex, removing the liquid, and pressing.

during said agitation partially coagulating drying said precipitate to form a dry flaky the latex, drying and pressing. powder, and pressing.

6. The process of molding articles, com- 8. The process of molding articles, com- 15 prising, forming a suspension of a filling prising, forming an emulsion of a filling 5 material, adding latex, partially coagulatmaterial and sulphur'for vulcanization, adding the latex, removing the liquid and drying latex, partially coagulating the latex, ing to form a flakyv powder, and pressing removing the liqu1d, drying to provide a said powder to molde form.v flaky powder containing the filler, rubber 20 7. The process of molding articles, comand sulphur for vulcanization, pressing and Y 1 Efiising, forming a suspension including a vulcanizing.

ing material, adding latex, partially co- GHAUNCEY 0; LOOMIS. agulating the latex to provide a precipitate, HORACE E. SZIUMP. M 

